Add ability to update multiple containers in the same task

[arbass22]

It would be helpful to be able to update the images if there are multiple containers in the same task definition. Currently, a user would have to chain multiple of these actions, creating multiple temp files with the iterative changes.

[majkelcc]

Just a though - support for updating multiple containers sounds like a bigger change and personally. What if we could try to make chaining multiple update actions easier? This could keep this action small and simple.

If passing the output file between each update action is what makes it hard, maybe the ability to work on the same file will solve this pain point?

I see two options:

1. Adding a flag overwriting the input file
2. A more flexible option to specify a path to the output file (could be the same as input)

Overwriting the input file would probably be the best if we're thinking about making chaining easier. This way the order of update actions doesn't matter, they can be moved/removed without breaking the rest of the workflow.